Determination of the theoretical and experimental electrochemical standard potentials of (o)-diphenols

In this research, the electrochemical standard potentials of the (o)-diphenol catechols (C-1-C-4) in methanol were calculated. This calculation was performed with the help of density functional theory (B3LYP), illustrating 3-21G, 6-31G(d,p) and 6-31G+(d,p) basis sets with the inclusion of entropic and thermo-chemical corrections to yield the free energies of redox reactions. For description of solvent, polarizable continuum model (PCM) was employed, while cyclic voltammetry (CV) was used to investigate the electrochemistry of the (o)-diphenol catechols at a glassy carbon electrode. The C-1-C-4 electrochemical standard potentials were computed with the average (root-mean-square) error of 0.012, 0.016 and 0.053V for 6-31G+(d,p), 6-31G(d,p) and 3-21G basis sets, respectively. This agreement mutually verified the accuracy of the experimental method and validity of the applied mathematical model. The correlation analysis between the experimental data and the theoretically calculated electrochemical standard potentials revealed the existence of notable relations between the calculated electrochemical standard potentials and HOMOs and LUMos eigenvalues of the examined compounds. In addition, the Mulliken atomic charges and the bond lengths of these compounds in methanol were calculated. (C) 2008 Elsevier B.V. All rights reserved.